Compositions comprising bone morphogenic proteins and truncated parathyroid hormone related peptide, and methods of inducing cartilage by administration of same

ABSTRACT

Compositions of proteins with chondrocyte and cartilaginous tissue inducing activity, as well as method of using those compositions, are disclosed. The compositions comprise one or more proteins of the transforming growth factor-β (TGF-β) superfamily of proteins, particularly bone morphogenetic proteins (BMPs), in combination with parathyroid hormone related polypeptide (PTHrP) or an equivalent PTH-like polypeptide. The compositions and methods are useful in the treatment of osteoarthritis, cartilage defects and in related tissue repair.

FIELD OF THE INVENTION

The present invention relates to novel methods and compositions forrepairing, reducing or preventing damage to cartilage and cartilaginoustissue. The methods and compositions may further be useful for theinduction and maintenance of cartilaginous tissue formation, woundhealing and cartilage and other tissue repair. These methods andcompositions may also be useful for augmenting the activity of bonemorphogenetic proteins. In particular, the present application relatesto the use of compositions comprising an osteogenic orcartilage-inducing member of the transforming factor beta TGF-β!superfamily of proteins, such as a bone morphogenetic protein BMP!, incombination with parathyroid hormone-related peptide PTHrP!. Thecompositions are useful for induction and maintenance of cartilaginoustissue, such as articular cartilage.

BACKGROUND OF THE INVENTION

The search for the molecule or molecules responsible for formation ofbone, cartilage, tendon and other tissues present in bone and othertissue extracts has led to the discovery of a novel set of moleculescalled the Bone Morphogenetic Proteins (BMPs). The structures of severalproteins, designated BMP-1 through BMP-15, have previously beenelucidated. The unique inductive activities of these proteins, alongwith their presence in bone, cartilage and/or other vital tissues,suggests that they are important regulators of bone and other tissuerepair processes, and may be involved in tissue formation, maintenanceand repair. There is a need to identify improved methods andcompositions for formation, maintenance and repair of such tissues.

Members of the bone morphogenetic protein family have been shown to beuseful for induction of cartilage and bone formation. For example, BMP-2has been shown to be able to induce the formation of new cartilageand/or bone tissue in vivo in a rat ectopic implant model, see U.S. Pat.No. 5,013,649; in mandibular defects in dogs, see Toriumi et al., Arch.Otolaryngol Head Neck Surg., 117:1101-1112 (1991); in femoral segmentaldefects in sheep, see Gerhart et al., Trans Orthop Res Soc, 16:172(1991). Other members of the BMP family have also been shown to haveosteogenic activity, including BMP-4, -6 and -7, see Wozney, BoneMorphogenetic Proteins and Their Gene Expression, in Cellular andMolecular Biology of Bone, pp. 131-167 (Academic Press, Inc. 1993). BMPproteins have also been shown to demonstrate inductive and/ordifferentiation potentiating activity on a variety of other tissues,including cartilage, tendon, ligament, neural tissue.

Parathyroid hormone-related peptide (PTHrP) is a protein which is knownexist in at least three isoforms of 139, 141 and 173 amino acids.Karaplis et al., Genes & Development, 8:277-289 (1994). PTHrP is highlyhomologous to the N-terminal fragment of parathyroid hormone (PTH), andbinds the same receptor as PTH. PTHrP appears to play a substantial rolein calcium metabolism by an autocrine/paracrine mechanism, and alsoappears to regulate embryonal development, vascular tone and nutrition.Tsukazaki et al., Calcif Tissue Int 57:196-200 (1995). It has recentlybeen shown that mice deficient in PTHrP exhibit abnormal cartilagematuration, indicating that PTHrP is an essential factor for chondrocytedevelopment and maturation. In Tsukazaki, it is reported that PTHrPexpression in articular cartilage varies in intensity and localizationduring development, while the PTH/PTHrP receptor is highly expressed inthe growth plate and in articular cartilage.

SUMMARY OF THE INVENTION

The present invention relates to compositions useful for inducingcartilaginous tissue formation in a patient in need of same, saidcompositions comprising one or more protein members of the transforminggrowth factor-β (TGF-β) superfamily together with parathyroid hormonerelated peptide (PTHrP), or an equivalent PTH-like polypeptide.Preferably, the compositions of the invention comprise at least oneprotein member of the bone morphogenetic protein (BMP) family andparathyroid hormone related peptide (PTHrP). In particular preferredembodiments, the composition comprises a bone morphogenetic protein isselected from the group consisting of BMP-2, BMP-4, BMP-5, BMP-7, BMP-12and BMP-13 together with PTHrP or an equivalent PTH-like polypeptide. Inthe most preferred embodiments, the compositions comprise BMP-2, BMP-13,heterodimers of BMP-2 and BMP-13 or combinations of the above, and PTHrPor an equivalent PTH-like polypeptide; especially preferred BMPs areBMP-2 and BMP-13. The compositions may further comprise one or moreadditional members of the BMP subfamily of proteins. In preferredembodiments of the invention, the PTHrP used is PTHrP1-34, a truncatedpeptide comprising the first 34 amino acids of the N-terminal portion ofPTH. In preferred embodiments of the invention, the compositionscomprise BMP-2 and one or more additional proteins selected from thegroup consisting of BMP-4, BMP-5, BMP-7, BMP-12 and BMP-13; or BMP-13and one or more additional proteins selected from the group consistingof BMP-2, BMP-4, BMP-5, BMP-7 and BMP-12 together with PTHrP1-34, PTHrPor another PTH-like polypeptide.

In other embodiments, the present invention relates to methods forinducing the formation and maintenance of cartilage in a patient, forexample a patient suffering from arthritis, particularly osteoarthritis,or a patient with an articular cartilage defect or other cartilaginoustissue defect, said method comprising administering to said patient aneffective amount of the above compositions. In a particular embodiment,the method of the present invention relates to a method for treatingarticular cartilage defects or damage in a patient in need of same, saidmethod comprising administering to said patient an effective amount ofthe above compositions. The invention further relates to methods forinducing the formation of cartilage and cartilaginous tissue comprisingadministering to a patient a composition comprising a member of theTGF-β superfamily of proteins and Parathyroid hormone-related peptide(PTHrP).

The methods and compositions of the present invention are thus usefulfor repairing, reducing or preventing damage to cartilage andcartilaginous tissue. The methods and compositions may further be usefulfor the induction and maintenance of cartilaginous tissue formation,wound healing and cartilage and other tissue repair for the induction ofcartilaginous tissue, such as articular cartilage, the meniscus, and thearticular surfaces of developing bone, or for the treatment of diseasesor defects of cartilaginous tissue, such as arthritis, particularlyosteoarthritis.

DETAILED DESCRIPTION OF THE INVENTION

The methods and compositions of the present invention comprise acombination of one or more proteins from the transforming growthfactor-β superfamily with one or more parathyroid hormone-relatedpeptides. The transforming growth factor-β superfamily is awell-characterized family of proteins involved in cellular proliferationand differentiation of cells into various tissues. Members of the TGF-βsuperfamily are generally dimeric in structure, comprising two monomericunits which are produced by proteolytic cleavage from a larger precursorprotein, of which the processed monomer represents the carboxyl terminalportion. The dimeric TGF-β proteins generally have molecular weights ofapproximately 20,000 to 35,000 and share a common cysteine pattern inthe mature protein region. See, for example, Sporn et al., Science,233:532-534 (1986) and the papers cited therein. The TGF-β superfamilyincludes several subgroups beside TGF-β1 through -β5, are the bonemorphogenetic proteins (BMPs), growth and differentiation factors(GDFs), the inhibins, as well as GDNF and Mullerian inhibitory substanceand other structurally related proteins. The TGF-β superfamily alsoincludes proteins from other species, which have been characterized andare highly conserved compared to the mammalian TGF-βs, including Vg1(Xenopus), see for example, Weeks and Melton, Cell, 51:861-867 (1987);Dpp, Screw and 60A (Drosophila), see for example Padgett et al., Nature(London), 325:81-84 (1987); Doctor et al., Dev. Biol. 151:591-505(1992); and more recently identified proteins including Univin (seaurchin), Dorsalin-1 (chicken) and Radar (Zebrafish). Other factors whichmay be effectively used in the composition include synthetic moleculesor fragments of a TGF-β superfamily member which are able to bind to aTGF-β receptor molecule.

Methods for production of numerous members of the TGF-β superfamilyuseful in the present invention are known and/or described in theliterature. For example, the structure and methods for production ofmany BMPs, including BMP-2, BMP-3, BMP-4, BMP-5, BMP-6 and BMP-7, aredisclosed, for instance, in U.S. Pat. Nos. 5,108,922; 5,013,649;5,116,738; 5,106,748; 5,187,076; and 5,141,905; BMP-8, disclosed in PCTpublication WO91/18098; BMP-9, disclosed in PCT publication WO93/00432;BMP-10, disclosed in PCT application WO94/26893; BMP-11, disclosed inPCT application WO94/26892; BMP-12 and BMP-13, disclosed in PCTapplication WO95/16035, or BMP-15, disclosed in co-pending patentapplication, Ser. No. 08/446,924, filed on May 18, 1995. The structureof Vgr-2, and the growth and differentiation factors GDFs!, includingthose described in PCT applications WO94/15965; WO94/15949; WO95/01801;WO95/01802; WO94/21681; WO94/15966; and others are also known. OtherTGF-β proteins which may be useful in the present invention include BIP,disclosed in WO94/01557; and MP52, disclosed in PCT applicationWO93/16099. Methods for production of heterodimeric proteins comprisingtwo distinct monomeric units, each comprising the amino acid sequence ofone of the above TGF-β proteins, are described in WO93/09229. Thedisclosures of all of the above applications are hereby incorporated byreference.

Parathyroid hormone-related peptide (PTHrP) is closely related instructure to parathyroid hormone. PTHrP is known to exist in at leastthree isoforms of 139, 141 and 173 amino acids. Karaplis et al., Genes &Development, 8:277-289 (1994). PTHrP is highly homologous to theN-terminal fragment of parathyroid hormone (PTH), and binds the samereceptor as PTH. The nucleotide and amino acid sequences of the PTHrPgene from rat, mouse and human are known and may be used to producePTHrP-like polypeptides useful in the present invention. See Karaplis etal., Mol. Endocrin. 4:441-446 1990! rat!; Mangin et al., PNAS 85:597-601(1988) human! and Mangin et al., Gene 95:195-202 (1990) mouse!; andMartin et al., Crit Rev Biochem Mal Biol 26:377-395 (1991).! In apreferred embodiment of the present invention, a variant of PTHrP isused in which one or more amino acids from the carboxy terminus has beendeleted. For example, PTHrP1-34, which comprises the first 34 aminoacids of PTHrP, is used in one preferred embodiment of the presentinvention. Also useful in the present invention are PTH-likepolypeptides which are equivalent to PTHrP1-34 in their ability toenhance survival of chondrocytes. Such PTH-like polypeptides mayinclude, for example, PTH, whether of human, porcine, bovine or othermammalian origin; variants of PTH, such as those described in Wingenderet al., U.S. Pat. No. 5,455,329; Wingender et al., U.S. Pat. No.5,457,047; and Schluter et al., U.S. Pat. No. 5,457,092, and thereferences cited therein; as well as variants of the above in which oneor more amino acids of PTH has been deleted from the carboxy and/oramino terminal portions of the molecule. The disclosures of the abovepublications are hereby incorporated by reference. PTH, PTHrP and theabove variants may be produced via recombinant DNA engineering using theknown sequences of the PTH and PTHrP proteins, or may be isolated bypurification.

The methods and compositions of the present invention may comprisesimultaneous or sequential administration of at least two active agents,a TGF-β protein and a parathyroid hormone-related peptide, to a patientor site in need of cartilage repair, formation or maintenance. Forsequential administration, one or both of the active agents may beencapsulated or otherwise maintained in contact with a carrier whichprovides for slow release of the agent. The methods and compositions maycomprise the active agents in a weight ratio of from about 90:10, toabout 10:90. Preferably the active agents are present in a weight ratioof about 70:30 to 30:70. Most preferred are methods and compositionscomprising the active agents in a weight ratio of about 50:50.

The compositions of the invention may comprise, in addition to a TGF-βprotein and a parathyroid hormone-related peptide, other therapeuticallyuseful agents including growth factors such as epidermal growth factor(EGF), transforming growth factor-α, activins, inhibins, plateletderived growth factor (PDGF), fibroblast growth factor (FGF), andfibroblast growth factor-4 (FGF-4), parathyroid hormone (PTH), leukemiainhibitory factor (LIF/HILDA/DIA), and insulin-like growth factors(IGF-I and IGF-II). Portions of these agents may also be used incompositions of the present invention. The compositions may also includean appropriate matrix for instance, for supporting the composition andproviding a surface for cartilage or for other connective tissue growth.The matrix may provide slow release of the protein and/or theappropriate environment for presentation thereof.

The methods and compositions of the present invention employ proteinswhich are able to induce cartilaginous tissue or other tissue formationin circumstances where such tissue is not normally formed, and hasapplication in the healing of cartilage, for example articular cartilagetears, deformities and other cartilage defects in humans and otheranimals. Such methods and compositions employing cartilaginous tissueinducing proteins may have prophylactic use in preventing damage tocartilaginous tissue, as well as use in the improved fixation ofcartilage to bone or other tissues, and in repairing defects tocartilage tissue. De novo cartilaginous tissue formation induced by acomposition of the present invention contributes to the repair ofcongenital, trauma induced, or other cartilage defects of other origin,and is also useful in surgery for attachment or repair of cartilage. Themethods and compositions of the invention may also be useful in thetreatment of arthritis and other cartilage defects. The methods andcompositions of the present invention can also be used in otherindications wherein it is desirable to heal or regenerate cartilagetissue. Such indications include, without limitation, regeneration orrepair of injuries to the articular cartilage. The methods andcompositions of the present invention may provide an environment toattract cartilage-forming cells, stimulate growth of cartilage-formingcells or induce differentiation of progenitors of cartilage-formingcells and chondrocytes.

The compositions and methods of the present invention may also be usefulfor treating cell populations, such as embryonic cells or stem cellpopulations, to enhance or enrich the growth, survival and/ordifferentiation of the cells into chondrocytes or other cell types. Inanother embodiment, the compositions and methods of the presentinvention may be used to treat chondrocytic cell lines, such asarticular chondrocytes, in order to maintain chondrocytic phenotype andsurvival of the cells. The treated cell populations may be useful forgene therapy applications.

The proteins useful in the methods of the present invention are usefulfor inducing the formation, maintenance and survival of chondrocytesand/or cartilaginous tissue. It is contemplated that these proteins mayhave the ability to induce the formation of other types of tissue, suchas tendon and ligament, as well. The cartilaginous tissue-inducingmethods and compositions provided herein also may include factorsencoded by the sequences similar to those of naturally-occurring TGF-βproteins, into which modifications are naturally provided (e.g. allelicvariations in the nucleotide sequence which may result in amino acidchanges in the polypeptide) or deliberately engineered. For example,synthetic polypeptides may wholly or partially duplicate continuoussequences of the amino acid residues of BMP-2 or BMP-13. Thesesequences, by virtue of sharing primary, secondary, or tertiarystructural and conformational characteristics with cartilaginous tissuegrowth factor polypeptides of naturally-occurring BMP-2 or BMP-13 maypossess cartilaginous or other tissue growth factor biologicalproperties in common therewith. Thus, they may be employed asbiologically active substitutes for naturally-occurring cartilaginoustissue inducing polypeptides in therapeutic methods and compositions.

The proteins useful in the present invention, or the DNA sequencesencoding therefor, may be engineered to provide one or more additionalcysteine residues to increase potential dimer formation, particularlyfor forming dimers of the TGF-β proteins. The resulting DNA sequencewould be capable of producing a "cysteine added variant" of the protein.Production of "cysteine added variants" of proteins is described in U.S.Pat. No. 5,166,322, the disclosure of which is hereby incorporated byreference. Other specific mutations of the sequences of cartilaginoustissue inducing proteins described herein involve modifications ofglycosylation sites. These modifications may involve O-linked orN-linked glycosylation sites. For instance, the absence of glycosylationor only partial glycosylation results from amino acid substitution ordeletion at asparagine-linked glycosylation recognition sites. Theasparagine-linked glycosylation recognition sites comprise tripeptidesequences which are specifically recognized by appropriate cellularglycosylation enzymes. These tripeptide sequences may beasparagine-X-threonine, asparagine-X-serine or asparagine-X-cysteine,where X is usually any amino acid except proline. A variety of aminoacid substitutions or deletions at one or both of the first or thirdamino acid positions of a glycosylation recognition site (and/or aminoacid deletion at the second position) results in non-glycosylation atthe modified tripeptide sequence. Additionally, bacterial expression ofprotein will also result in production of a non-glycosylated protein,even if the glycosylation sites are left unmodified.

The methods of the present invention for inducing cartilaginous tissueformation may comprise administering to a patient an effective amount ofa composition comprising one or more protein members of the transforminggrowth factor-β (TGF-β) superfamily together with parathyroid hormonerelated peptide (PTHrP), or an equivalent PTH-like polypeptide.Alternatively, the methods of the present invention for inducingcartilaginous tissue formation may comprise heterodimers comprised oftwo distinct monomeric units, each of which has the amino acid sequenceof a member of the TGF-β superfamily, together with PTHrP, or anequivalent PTH-like polypeptide. Preferably, the compositions of theinvention comprise one or more members of the bone morphogenetic protein(BMP) family, together with PTHrP or an equivalent PTH-like polypeptide.In particular preferred embodiments, the composition comprises a bonemorphogenetic protein selected from the group consisting of BMP-2,BMP-4, BMP-5, BMP-7, BMP-12 and BMP-13, or heterodimers of the above,together with PTHrP or an equivalent PTH-like polypeptide. In the mostpreferred embodiments, the composition comprises BMP-2, BMP-13,heterodimers of BMP-2 and BMP-13 or combinations of the above, and PTHrPor an equivalent PTH-like polypeptide. The above compositions mayoptionally comprise one or more additional proteins which are members ofthe TGF-β superfamily, preferably of the BMP family of proteins. Inpreferred embodiments, the composition comprises BMP-2 and one or moreadditional proteins selected from the group consisting of BMP-4, BMP-5,BMP-7, BMP-12, BMP-13 and heterodimers of the above; or BMP-13 and oneor more additional proteins selected from the group consisting of BMP-2,BMP-4, BMP-5, BMP-7, BMP-12 and heterodimers of the above; each togetherwith PTHrP or an equivalent PTH-like polypeptide. As discussed above,these compositions may be used to induce the formation, maintenance andsurvival of chondrocytes and/or cartilaginous tissue or other tissue. Itis contemplated that such compositions may also be used for articularcartilage repair, wound healing and other tissue repair, such as skinrepair. It is further contemplated that proteins of the invention mayincrease neuronal survival and therefore be useful in transplantationand treatment of conditions exhibiting a decrease in neuronal survival.Compositions and methods of the invention may further be useful forinduction and repair of other tissue, including wound healing.

In a preferred embodiment of the present invention, more than oneprotein of the TGF-β superfamily may be used together with PTHrP toenhance the induction, maintenance and differentiation of one or morecell and/or tissue types, including cartilaginous tissue. For example, acomposition comprising both BMP-2 and BMP-13 implanted together withPTHrP may give rise to both bone and cartilaginous tissue. Such acomposition may be useful for treating defects of the junction betweencartilage and bone, causing cartilage and bone to form simultaneously atcontiguous anatomical locations, and may therefore be useful forregenerating tissue at the site of cartilage attachment to bone.

It is contemplated that the methods and compositions of the inventionmay also be useful in wound healing, such as skin healing and relatedtissue repair. The types of wounds include, but are not limited to bums,incisions and ulcers. (See, e.g. PCT Publication WO84/01106 fordiscussion of wound healing and related tissue repair).

The methods and compositions of the invention further compriseheteromolecules comprised of different TGF-β moieties, in combinationwith PTHrP or an equivalent PTH-like polypeptide. Preferably, theheteromolecule is a heterodimer, for example, of two monomers eachcomprising the amino acid sequence of a BMP protein. For example, amethod and composition of the invention may comprise a disulfide linkeddimer comprising a BMP-2 protein subunit and a subunit from one of theother BMP proteins described above. Thus, in a particular embodiment,the present invention comprises compositions and methods employing aheterodimer wherein one subunit comprises the amino acid sequence ofBMP-2, and one subunit comprises an amino acid sequence for a bonemorphogenetic protein selected from the group consisting of BMP-3,BMP-4, BMP-5, BMP-6, BMP-7, BMP-8, BMP-9, BMP-10, BMP-11, BMP-12, BMP-13or BMP-15. Further embodiments may comprise a heterodimer of otherdisulfide bonded TGF-β moieties, including VGR-2, MP52, MIS, activin andTGF-β. For example, the heterodimer may comprise one subunit comprisingthe amino acid sequence of BMP-2 or BMP-13, and the other subunit maycomprise the amino acid of activin. Further, compositions of the presentinvention may be combined with other agents beneficial to the treatmentof the defect, wound, or tissue in question.

It is expected that the compositions and methods of the invention mayact in concert with or perhaps synergistically with administration ofother related proteins and growth factors. Further therapeutic methodsand compositions of the invention therefore comprise a therapeuticamount of at least one of the BMP proteins, whether homodimeric orheterodimeric, in combination with PTHrP or an equivalent PTH-likepolypeptide, and other growth factors.

The preparation and formulation of such physiologically acceptableprotein compositions, having due regard to pH, isotonicity, stabilityand the like, is within the skill of the art. The therapeuticcompositions are also presently valuable for veterinary applications dueto the lack of species specificity in TGF-β proteins. Particularlydomestic animals and thoroughbred horses in addition to humans aredesired patients for such treatment with the compositions of the presentinvention.

The therapeutic method includes administering the composition topically,systemically, or locally as an injectable and/or implant or device. Whenadministered, the therapeutic composition for use in this invention is,of course, in a pyrogen-free, physiologically acceptable form. Further,the composition may desirably be encapsulated or injected in a viscousform for delivery to the site of tissue damage. Topical administrationmay be suitable for wound healing and tissue repair. Therapeuticallyuseful agents other than the proteins which may also optionally beincluded in the composition as described above, may alternatively oradditionally, be administered simultaneously or sequentially with thecomposition in the methods of the invention. In addition, thecompositions of the present invention may be used in conjunction withpresently available treatments for cartilage injuries, such as suture(e.g., vicryl sutures or surgical gut sutures, Ethicon Inc., Somerville,N.J.) or cartilage allograft or autograft, in order to enhance oraccelerate the healing potential of the suture or graft. For example,the suture, allograft or autograft may be soaked in the compositions ofthe present invention prior to implantation. It may also be possible toincorporate the protein or composition of the invention onto suturematerials, for example, by freeze-drying.

The compositions of the present invention may include an appropriatematrix and/or sequestering agent as a carrier. For instance, the matrixmay support the composition or provide a surface for cartilaginoustissue formation and/or other tissue formation. The matrix may provideslow release of the protein and/or the appropriate environment forpresentation thereof. The sequestering agent may be a substance whichaids in ease of administration through injection or other means, or mayslow the migration of protein from the site of application.

The choice of a carrier material is based on biocompatibility,biodegradability, mechanical properties, cosmetic appearance andinterface properties. The particular application of the compositionswill define the appropriate formulation. Potential matrices for thecompositions may be biodegradable and chemically defined. Furthermatrices are comprised of pure proteins or extracellular matrixcomponents. Other potential matrices are nonbiodegradable and chemicallydefined. Preferred matrices include collagen-based materials, includingsponges, such as Helistat® (Integra LifeSciences, Plainsboro, N.J.), orcollagen in an injectable form, as well as sequestering agents, whichmay be biodegradable, for example hyaluronic acid derived. Biodegradablematerials, such as cellulose films, or surgical meshes, may also serveas matrices. Such materials could be sutured into an injury site, orwrapped around the cartilage.

Another preferred class of carrier are polymeric matrices, includingpolymers of poly(lactic acid), poly(glycolic acid) and copolymers oflactic acid and glycolic acid. These matrices may be in the form of asponge, or in the form of porous particles, and may also include asequestering agent. Suitable polymer matrices are described, forexample, in WO93/00050, the disclosure of which is incorporated hereinby reference.

Preferred families of sequestering agents include blood, fibrin clotand/or cellulosic materials such as alkylcelluloses (includinghydroxyalkylcelluloses), including methylcellulose, ethylcellulose,hydroxyethylcellulose, hydroxypropylcellulose,hydroxypropyl-methylcellulose, and carboxymethylcellulose, the mostpreferred being cationic salts of carboxymethylcellulose (CMC). Otherpreferred sequestering agents include hyaluronic acid, sodium alginate,poly(ethylene glycol), polyoxyethylene oxide, carboxyvinyl polymer andpoly(vinyl alcohol). The amount of sequestering agent useful herein is0.5-20 wt %, preferably 1-10 wt % based on total formulation weight,which represents the amount necessary to prevent desorbtion of theprotein from the polymer matrix and to provide appropriate handling ofthe composition, yet not so much that the progenitor cells are preventedfrom infiltrating the matrix, thereby providing the protein theopportunity to assist the activity of the progenitor cells.

Additional optional components useful in the practice of the subjectapplication include, e.g. cryogenic protectors such as mannitol,sucrose, lactose, glucose, or glycine (to protect the protein fromdegradation during lyophilization), antimicrobial preservatives such asmethyl and propyl parabens and benzyl alcohol; antioxidants such asEDTA, citrate and BHT (butylated hydroxytoluene); and surfactants suchas poly(sorbates) and poly(oxyethylenes); etc.

As described above, the compositions of the invention may be employed inmethods for treating a number of cartilage defects, such as theregeneration of cartilaginous tissue in areas of cartilage damage, toassist in repair of tears of cartilage tissue, and various other typesof tissue defects or wounds. These methods, according to the invention,entail administering to a patient needing such cartilaginous tissue orother tissue repair, a composition comprising an effective amount of anosteogenic or cartilage-inducing member of the transforming factor betaTGF-β! superfamily of proteins, such as a bone morphogenetic proteinBMP!, preferably BMP-2, BMP-4, BMP-5, BMP-7, BMP-12 and BMP-13, incombination with parathyroid hormone-related peptide PTHrP! anequivalent PTH-like polypeptide.

In another embodiment, the methods may entail administration of aheterodimeric protein in which each of the monomers comprises the aminoacid sequence of an osteogenic or cartilage-inducing member of the TGFβsuperfamily of proteins, such as a BMP, particularly, BMP-2, BMP-4,BMP-5, BMP-7, BMP-12 and BMP-13, in combination with PTHrP or anequivalent PTHrP-like polypeptide. In a preferred embodiment, each ofthe monomers is selected from the group consisting of BMP-2, BMP-4,BMP-5, BMP-7, BMP-12 and BMP-13.

Thus, a further aspect of the invention is a therapeutic method andcomposition for inducing or maintaining chondrocytes or cartilaginoustissue, for repairing cartilaginous tissue, for repairing cartilage aswell as treating arthritis and other conditions related to arthritis orcartilage defects. Such compositions comprise a therapeuticallyeffective amount of one or more osteogenic or cartilaginous tissueinducing proteins, such as BMP-2 or BMP-13, in combination with PTHrP oran equivalent PTH-like polypeptide, in admixture with a pharmaceuticallyacceptable vehicle, carrier or matrix.

The dosage regimen will be determined by the attending physicianconsidering various factors which modify the action of the composition,e.g., amount of cartilaginous tissue desired to be formed, the site ofcartilaginous tissue damage, the condition of the damaged cartilaginoustissue, the size of a wound, type of damaged tissue, the patient's age,sex, and diet, the severity of any infection, time of administration andother clinical factors. The dosage may vary with the type of matrix usedin the reconstitution and the types of additional proteins in thecomposition. The addition of other known growth factors, such as IGF-I(insulin like growth factor I), to the final composition, may alsoaffect the dosage.

Progress can be monitored by periodic assessment of chondrocytesurvival, cartilaginous tissue formation, or cartilaginous tissue growthand/or repair. The progress can be monitored by methods known in theart, for example, X-rays, arthroscopy, histomorphometric determinationsand tetracycline labeling.

The following examples illustrate practice of the present invention inusing the compositions and methods described above. The methods areuseful for producing, recovering and maintaining chondrocytes and/orhuman cartilaginous tissue inducing protein, employing the methods andcompositions of cartilaginous tissue inducing proteins and PTHrP andequivalent PTH-like polypeptides. Although the examples demonstrate theinvention with respect to BMP-2 and PTHrP1-34, with minor modificationswithin the skill of the art, the same results may be attainable withother TGF-β proteins, particularly other BMPs, as well as equivalentPTH-like polypeptides.

EXAMPLES 1. Effect of Combination of BMP and PTHrP on Expression andMaintenance of Cartilage Specific mRNA.

PTHrP was tested for its effect on cell lines derived from E13 mouselimb buds either alone or in combination with BMP-2. Cells were grown toconfluence in DME medium supplemented with 10% fetal calf serum (FCS).At confluence, cells were transferred to DME medium supplemented with 1%FCS and cultured for 1, 2, 4 or 8 days in the presence of either BMP-2(100 ng/ml), PTHrP1-34 (100 ng/ml)(Peninsular Laboratories Inc). or acombination of BMP-2 and PTHrP1-34. Northern analysis was used todetermine expression of tissue specific mRNAs for cartilage(proteoglycan core protein, collagen type II and decorin), bone(osteocalcin, alkaline phosphatase and collagen type I) and hypertrophiccartilage (collagen type X). Treatment of limb bud cells with acombination of BMP-2 and PTHrP1-34 induced and maintained expression ofproteoglycan core protein and collagen type II. Expression ofosteocalcin, collagen type I, alkaline phosphatase and collagen type Xwere all strongly inhibited by treatment with the combination of BMP-2and PTHrP1-34, compared with treatment with BMP-2 alone. PTHrP1-34 alonedid not induce expression of any of these RNAs.

These observations, combined with the reported localization of PTHrP1-34in articular cartilage indicate that a combination of BMP-2 andPTHrP1-34 induces the formation and maintenance of cartilaginous tissue,rather than hypertrophic cartilage or bone. This conclusion is supportedby the reported localization of PTHrP in articular cartilage and thephenotype of mice containing mutations to the PTHrP1-34 gene.

Example 2 Cartilage Induction Using BMP and PTHrP

Combinations of other BMPs and PTHrP1-34 are tested for their effect oncell lines derived from E13 mouse limb buds as described in Example 1above. Cells are grown to confluence on medium containing DMEsupplemented with 1% fetal calf serum. The cells are treated with (a)BMP, such as BMP-13, alone; (b) PTHrP alone; or (c) combinations of BMPand PTHrP; in varying doses from less than 1 ng/ml up to about 5.0×10³ng/ml. After 10 days of treatment, histologic and Northern analyses areperformed for expression of cartilage and bone markers as described inExample 1 above.

Example 3 Full Thickness Articular Cartilage Repair Model

A full thickness articular cartilage defect model in thefemoral-patellar joint of adult rabbits is used to evaluate the abilityof the combination of BMPs and PTHrP to affect cartilage and bonerepair. Adult New Zealand White rabbits are anesthetized and preparedfor sterile surgery. A 3×3 mm defect through articular cartilage andinto underlying subchondral bone is drilled into the patellar groove ofthe knee joint. The defect is either left empty, filled with collagensponge (controls), or with collagen sponge soaked with 10 μg rhBMP-2alone, PTHrP alone, another BMP protein alone, or a combination of BMPand PTHrP (experimental). The incision is closed and animals are allowedfree movement within their cages for 4 weeks. After 4 weeks the animalsare humanely euthanatized and the articular cartilage/subchondral bonedefect is evaluated histologically for tissue architecture, quantity andquality of repair tissue. Northern analysis is performed for additionalphenotyping.

What is claimed is:
 1. A composition comprising:(a) at least one proteinmember of the bone morphogenetic protein (BMP) family of proteins; and(b) a truncated parathyroid hormone related peptide (PTHrP) comprisingamino acids 1 to 34 of PTHrP; said composition having the activity ofinducing the formation or maintenance of cartilaginous tissue in apatient when administered to said patient.
 2. The composition of claim1, wherein the bone morphogenetic protein is selected from the groupconsisting of BMP-2, BMP-4, BMP-5, BMP-7, BMP-12 and BMP-13.
 3. Thecomposition of claim 2, wherein the bone morphogenetic protein is BMP-2.4. The composition of claim 3, wherein said composition furthercomprises one or more additional proteins which are members of the BMPsubfamily of proteins.
 5. The composition of claim 4, wherein theadditional proteins are selected from the group consisting of BMP-4,BMP-5, BMP-7, BMP-12 and BMP-13.
 6. The composition of claim 2, whereinthe bone morphogenetic protein is BMP-13.
 7. The composition of claim 6,wherein said composition further comprises one or more additionalproteins which are members of the BMP subfamily of proteins.
 8. Thecomposition of claim 7, wherein the additional proteins are selectedfrom the group consisting of BMP-2, BMP-4, BMP-5, BMP-7 and BMP-12.
 9. Amethod for inducing the formation or maintenance of cartilaginous tissuein a patient, comprising administering to the patient an effectiveamount of the composition of claim
 1. 10. A method according to claim 9,wherein the patient is suffering from arthritis.
 11. A method accordingto claim 9, wherein the patient is suffering from an articular cartilagedefect or damage.
 12. A composition comprising:(a) at least one proteinmember of the transforming growth factor-β (TGF-β) superfamily selectedfrom the group consisting of Bone Morphogenetic Protein-2 (BMP-2), BoneMorphogenetic Protein-13 (BMP-13), heterodimers of BMP-2 and BMP-13 andcombinations of the above; and (b) a truncated parathyroid hormonerelated peptide (PTHrP) comprising amino acids 1 to 34 of PTHrP; saidcomposition having the activity of inducing the formation or maintenanceof cartilaginous tissue in a patient when administered to said patient.13. The composition of claim 12 wherein the TGF-β superfamily member isBMP-2.
 14. The composition of claim 12 wherein the TGF-β superfamilymember is BMP -13.
 15. A method for inducing the formation ormaintenance of cartilaginous tissue in a patient, comprisingadministering to the patient an effective amount of the composition ofclaim
 12. 16. A method according to claim 15, wherein the patient issuffering from arthritis.
 17. A method according to claim 15, whereinthe patient is suffering from an articular cartilage defect or damage.